<p>
<i>Impulsivity</i>, or the tendency to act prematurely without
foresight, has been linked to a diverse range of pathological
conditions. Foresight refers to the ability to envision future
rewards and events (i.e. prospectively sample) and has been
associated with decreased impulsivity. One form of impulsivity is
measured by the ability to delay gratification and is often studied
in the framework of Delay Discounting (DD). DD provides the means to
study impulsivity in a number of pathological conditions. However,
whether impulsivity precedes the development of pathological states
or results from the pathological state itself is not fully
understood. This necessitates an understanding of neurobiological
mechanisms contributing to decision making in both non-impulsive as
well as impulsive populations of individuals.
</p>
<p>
Animal models allow invasive techniques to be used to dissect the
neurocircuitry involved in decision making. Given that the
decision-making process is an ongoing process rather than an isolated
event, optogenetics provide the temporal and spatial specificity
necessary for evaluating brain region specific contributions to
decision making in DD. In the present study, optogenetics were used
to assess the contribution of the medial Prefrontal Cortex (mPFC), a
brain region involved in ‘goal-directed’ behavior, in the
planning of future choices (i.e. prospective plans) and subsequent
measures of impulsivity in an adjusting amount DD procedure.
Optogenetic inhibition of mPFC was conducted in Wistar rats during
different epochs of a DD task in order to assess how mPFC affects
planning behavior in a population of rat not considered to be highly
impulsive. Although no direct effects on planning behavior (e.g.
consistency) were observed, inhibiting mPFC after a trial has been
initiated and directly before a choice was made (Epoch 2) was
observed to increase measures of impulsivity in comparison to days
where no optogenetic manipulation occurred in a delay-specific
manner. This suggests that mPFC differentially contributes to
decision making at different delays. A pattern of associations
between choice latency, impulsivity, and consistency began to emerge
for inactivation occurring in Epoch 2, suggesting that mPFC contributes to some aspect of
planning choices during this epoch. Moreover, these results indicate
that mPFC is involved in decision making in Wistar Rats.
Understanding the direct role that mPFC plays in promoting choices of
delayed rewards provides a neurobiological target for treatment aimed
at reducing impulsivity in the clinical population.</p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/8016389 |
| Date | 10 June 2019 |
| Creators | Shelby M White (6615890) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/Optogenetic_Inhibition_of_the_mPFC_During_Delay_Discounting/8016389 |
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